Smoking article filter with amorphous magnesium carbonate

ABSTRACT

A filter for a smoking article includes filtration material and an amorphous magnesium carbonate material contained within the filtration material. A smoking article includes a smokable material and the filter downstream of the smokable material.

This disclosure relates to smoking article filters containing amorphous magnesium carbonate.

Combustible smoking articles, such as cigarettes, typically have shredded tobacco, usually in cut filler form, surrounded by a paper wrapper forming a tobacco rod. A cigarette is employed by a smoker by lighting one end of the cigarette and burning the tobacco rod. The smoker then receives mainstream smoke by drawing on the opposite end or mouth end of the cigarette, which typically contains a filter. The filter is positioned to entrap some constituents of mainstream smoke before the mainstream smoke is delivered to a smoker.

A number of smoking articles in which an aerosol generating substrate, such as tobacco, is heated rather than combusted have also been developed. In heated smoking articles, the aerosol is generated by heating the aerosol generating substrate. Known heated smoking articles include, for example, smoking articles in which an aerosol is generated by electrical heating or by the transfer of heat from a combustible fuel element or heat source to an aerosol generating substrate. During smoking, volatile compounds are released from the aerosol generating substrate by heat transfer from the heat source and entrained in air drawn through the smoking article. As the released compounds cool they condense to form an aerosol that is inhaled by the consumer. Also known are smoking articles in which a nicotine-containing aerosol is generated from a tobacco material, tobacco extract, or other nicotine source, without combustion, and in some cases without heating, for example through a chemical reaction. Such non-combustible smoking articles may also include a filter positioned to adsorb smoke constituents before the mainstream smoke is delivered to a user.

Filters in smoking articles, whether combustible or non-combustible, may contain activated carbon to remove selected constituents from smoke or aerosol. Activated carbon granules may generate carbon fines during transport, handling and loading of the activated carbon granules. Particle breakthrough may occur in filters containing activated carbon granules due in part to the presence of the carbon fines. Activated carbon powder is not used in smoking articles because its size is too small to be retained by filter material such as cellulose acetate tow.

Activated carbon may negatively affect the taste of the smoke or aerosol formed by the tobacco or aerosol generating substrate of the smoking article. A consumer may perceive this taste to be “dry” or have “carbon” notes.

Magnesium carbonate naturally occurs in a regular crystalline form, either as a salt or a mineral. Magnesium carbonate (MgCO₃) is an inorganic salt that is a white solid. Several hydrated and basic forms of magnesium carbonate exist as minerals.

It would be desirable to provide a filter for a smoking article that may selectively remove constituents from smoke or aerosol while not negatively affecting the taste of the smoke or aerosol. It would be desirable to provide a filter for a smoking article that may regulate or maintain a relative humidity or moisture level within the filter and smoking article. It would be desirable to provide filter for a smoking article that may not contain activated carbon or contain a reduced amount of activated carbon. It would be desirable to provide filter for a smoking article that may contain a stable sorbent that may remain physically in-place within the filter.

Various aspects of the present invention provide a filter for a smoking article. The filter includes filtration material and an amorphous magnesium carbonate material contained within the filtration material. A smoking article includes a smokable material and the filter downstream of the smokable material. The amorphous magnesium carbonate material may be hygroscopic.

Amorphous magnesium carbonate is distinct from typical crystalline magnesium carbonate. Amorphous magnesium carbonate may be synthesized and exhibit a unique structure of pores that may be substantially in the sub-10 nanometer or sub-6 nanometer size range and also exhibit an extraordinary high surface area (such as greater than about 100 m²/g, or greater than about 300 m²/g). Typical crystalline magnesium carbonate has a surface area in a range from 4-15 m²/g. The extraordinary high surface area of amorphous magnesium carbonate places this material in an exclusive class of high surface area nanomaterials, such as zeolites and carbon nanotubes.

The amorphous magnesium carbonate material may have a high surface area that may be greater than 100 m²/g. The amorphous magnesium carbonate material may be porous. Pore size of the amorphous magnesium carbonate material may be characterized as generally microporous (about 2 nm or less) or generally mesoporous (about 2 nm to about 50 nm). The amorphous magnesium carbonate material may have an average particle size greater than about 100 micrometres (or greater than about 140 mesh).

Advantageously, combining the amorphous magnesium carbonate material with a filter for a smoking article may selectively remove constituents from smoke or aerosol and may not negatively affect the taste of the smoke or aerosol. Advantageously, the amorphous magnesium carbonate material may be sized to remain physically secured within the filter. Advantageously, the amorphous magnesium carbonate material may be hygroscopic and absorb excess humidity or release contained water to maintain moisture levels within the smoking article. Advantageously, combining the amorphous magnesium carbonate material with a filter for a smoking article may eliminate or reduce an amount of activated carbon or other sorbent material needed within the smoking article filter. Advantageously, the amorphous magnesium carbonate material may exhibit a light or white color that may match the color of the filtration material, in addition, the amorphous magnesium carbonate material may by generally recognized as safe (GRAS) by regulatory authority and be environmentally friendly.

The phrase “BET surface area” refers to specific surface area determined from a Brunauer-Emmet-Teller (“BET”) analysis of nitrogen adsorption isotherms.

The phrase “x-ray amorphous” refers to an amorphous material form that may be characterized using x-ray diffraction. The terms “x-ray amorphous” and “amorphous” are used here interchangeably. The terms “amorphous magnesium carbonate” and “x-ray amorphous magnesium carbonate” are used here interchangeably.

The term “hygroscopic” refers to a material property of attracting and holding water molecules from the surrounding, usually at normal or room temperature, environment. This may be achieved through either absorption or adsorption.

As used herein, a “smokable material” refers to a material that generates an aerosol deliverable to a user of a smoking article when the material is placed in a smoking article and the smoking article is employed by a user.

A filter for a smoking article includes filtration material and an amorphous magnesium carbonate material contained within the filtration material. A smoking article includes a smokable material and the filter downstream of the smokable material.

The amorphous magnesium carbonate material may selectively remove constituents from smoke or aerosol when the smoking article is consumed. The amorphous magnesium carbonate material may be contained within any useful filter configuration that may contain the amorphous magnesium carbonate within the filter.

The amorphous magnesium carbonate material may be hygroscopic and will physically adsorb water. The physical adsorption of water does not form hydrated forms of the amorphous magnesium carbonate. The amorphous and hygroscopic magnesium carbonate material may physically adsorb at least about 0.6 mmol water/g, or at least 1 mmol water/gram, or at least 2 mmol water/gram, at a relative humidity of about 3% at room temperature (about 27 degree Celsius) and one Atm. The amorphous and hygroscopic magnesium carbonate material may physically adsorb at least about 1.5 mmol water/g, or at least 2 mmol water/gram, or at least 4 mmol water/gram, at a relative humidity of about 10% at room temperature (about 27 degree Celsius) and one Atm. The amorphous and hygroscopic magnesium carbonate material may physically adsorb at least about 10 mmol water/g, or at least 15 mmol water/gram, or at least 20 mmol water/gram, at a relative humidity of about 90% at room temperature (about 27 degree Celsius) and one Atm.

The amorphous and hygroscopic magnesium carbonate material may physically desorb or release the bound water be either heating the material or reducing the relative humidity. The amorphous and hygroscopic magnesium carbonate material may physically desorb or release up to about 15% wt, or up to about 20% wt, or up to about 25% wt of its water bound content when the relative humidity (surrounding the amorphous and hygroscopic magnesium carbonate material) is reduced from 95% to 5% at room temperature (about 27 degree Celsius) and one Atm. Thus, the amorphous and hygroscopic magnesium carbonate material may absorb excess humidity or release contained water to maintain moisture levels within the smoking article.

The amorphous magnesium carbonate material may be characterized utilizing x-ray diffraction. Amorphous magnesium carbonate material is described in U.S. Patent Application Publication US2015/0298984. Water adsorption and desorption may be characterized utilizing nitrogen and water vapour sorption isotherms with the Dubinin-Astakhov (D-A) model, x-ray diffraction and BET surface area test methods for amorphous magnesium carbonate characterization and surface characterization are all described therein.

BET analysis of surface area (BET surface area) may be determined using an N₂ adsorption isotherm at −196° C. obtained in a volumetric Autosorb-6B apparatus from Quantachrome generally as described in the following (i) Gregg S J, Sing K S W. Adsorption, Surface Science and Porosity. Academic Press, New York 1982; (ii) Rouquerol F, Rouquerol J, Sing K. Adsorption by powders and porous solids. Principles, methodology and applications. Academic Press, 1999; and (iii) Linares-Solano A, Salinas-Martinez de Lecea C, Alca{umlaut over (n)}iz-Monge J, Cazorla-Amorós D. For example, the specific surface area may be determined according to ISO 9277 (2010): Determination of the specific surface area of solids by gas adsorption—BET method. Methods for determining specific surface area of microporous materials (type I isotherms) provided in an annex of ISO 9277 (2010) may be particularly useful for determining specific surface area.

Different suitable methods may be employed, individually or combined, to confirm and quantify the amorphous magnesium carbonate content of the material. These methods can include, but are not limited to, XPS (x-ray photoelectron spectroscopy), Raman spectroscopy, XRD (x-ray diffraction), FTIR (Fourier transform infrared spectroscopy), NMR spectroscopy (nuclear magnetic resonance spectroscopy), ICP-MS (inductively coupled plasma mass spectrometry), EDS (energy-dispersive X-ray spectroscopy), TEM (transmission electron microscopy) ED (electron diffraction) and TGA (Thermogravimetric analysis). Raman spectroscopy may be employed to reveal the presence of amorphous magnesium carbonate (by the presence of the so-called Boson peak at low wavenumbers which is characteristic for amorphous materials, and the distinctive carbonate peak at about 1100 cm−1). To confirm the presence and determine the amount of magnesium carbonate in a material, XPS analysis can be employed in the following manner: The magnesium carbonate content in the material can be determined by elemental analysis using XPS, and energy resolved spectrum analysis using the same technique can be used to distinguish between crystalline and amorphous magnesium carbonate: the electron binding energy in the Mg 2 s orbital of amorphous magnesium carbonate is expected to be about 90.7 eV while the binding energy generally is expected to be about 91.5 eV or higher for crystalline magnesium carbonates.

XRD analysis may be employed for crystal phase determination of the constituents of a material where the amorphous magnesium carbonate content can be quantified in relation to the crystalline content. In particular, the presence of amorphous magnesium carbonate can be confirmed by XRD. In an XRD measurement amorphous magnesium carbonate gives rise to either broad halos or just noisy flat signals in the 20 window between about 10° and 20° as well as between about 25° and 40° when the diffractometer uses CuKα radiation. When the remaining part of a material, consisting of materials other than amorphous magnesium carbonate (including impurities or other elements introduced on purpose), such materials will give rise to peaks in the XRD pattern, provided that they are crystalline.

The amorphous magnesium carbonate material may have an extraordinary surface area or BET surface area. The amorphous magnesium carbonate material may have a BET surface area of at least about 200 m²/g, or at least about 300 m²/g, or at least about 500 m²/g. The amorphous and magnesium carbonate material may have a BET surface area within a range from about 300 m²/g to about 1200 m²/g, within a range from about 600 m/g to about 1000 m²/g, or within a range from about 700 m²/g to about 900 m²/g, or about 800 m²/g. For comparison, typical crystalline magnesium carbonate has a surface area or BET surface area of about 10 m²/g or less.

The amorphous magnesium carbonate material is porous. Pore size of the amorphous magnesium carbonate material may be characterized as generally microporous (about 2 nm or less) or generally mesoporous (about 2 nm to about 50 nm). The amorphous and magnesium carbonate material may exhibit a unique structure of pores that is substantially in the sub-6 nm size range. The amorphous and magnesium carbonate material may have at least about 98% of pore diameter being less than about 10 nm, or at least about 98% of pore diameter being less than about 6 nm.

The amorphous magnesium carbonate material may have a cumulative volume of pores with a diameter smaller than about 10 nm of at least about 0.02 cm³/g, preferably of at least about 0.4 cm³/g, and even more preferably of at least about 0.8 cm³/g, and a cumulative volume of pores with a diameter smaller than about 10 nm up to about 1.5 cm³/g, or more preferably up to about 2 cm³/g or most preferably up to about 3 cm³/g. The pore size distribution and the cumulative pore volume may be determined by density functional theory (DFT) calculations on the adsorption isotherm. As appreciated by the skilled person, the unique distribution of micro and meso pores according to the present invention may be described with other parameters and can be based on other types of measurements than described herein.

The amorphous magnesium carbonate material may be formed synthetically and referred to as “synthetic amorphous magnesium carbonate”. One example synthesis consists of: placing MgO powder in a glass container with methanol, then applying CO₂ under pressure into the glass container allowing the reaction to occur at about 50 degrees Celsius. A gel forms and is allowed to solidify and dry at about 70 degrees Celsius. The dry material defines the synthetic amorphous magnesium carbonate, having the physical properties described above, and may be utilized as described herein.

The amorphous magnesium carbonate material may selectively remove one or more constituents from smoke passing through a filter containing the amorphous magnesium carbonate material. The amorphous magnesium carbonate material may remove the one or more constituents from smoke by, for example, binding, adsorption, and the like. Preferably, amorphous magnesium carbonate material contained in smoking article filters may remove formaldehyde. The amorphous magnesium carbonate material contained in smoking article filters may remove benzene. The amorphous magnesium carbonate material contained in smoking article filters may remove water.

The amorphous magnesium carbonate material may have an average particle size in a range from about 100 micrometres (about 140 mesh) to about 2000 micrometres (about 10 mesh), or from about 200 micrometres (about 70 mesh) to about 1500 micrometres (about 14 mesh), or from about 400 micrometres (about 40 mesh) to about 1000 micrometres (about 18 mesh). This relatively large particle size may assist in containing the amorphous magnesium carbonate material within the filter. This relatively large particle size may assist in preventing breakthrough of the amorphous magnesium carbonate material out of the filter during consumption.

The use of the term “diameter” in the context of particles of amorphous magnesium carbonate material may be considered to refer to the average of the length, width and height of the particles within a population of particles. Alternatively, “diameter” can be considered to be a range based on size of sieves through which a population of particles of amorphous magnesium carbonate material may pass, with the smallest tested sieve through which the particles pass being the maximum “diameter”, and through which amorphous magnesium carbonate material particles do not pass, with the largest tested sieve through which the particles do not pass being the minimum “diameter.”

Preferably filters and smoking articles that include the amorphous magnesium carbonate material having an average particle size in a range from about 100 micrometres (about 140 mesh) to about 2000 micrometres (about 10 mesh), or from about 400 micrometres (about 40 mesh) to about 1000 micrometres (about 18 mesh) may exhibit less particle breakthrough than currently available filters and smoking articles that include activated carbon.

Particle breakthrough can be determined by any suitable process. Preferably, particle breakthrough is measured via dry puff (unlit) analysis on a filter containing sorbent. Particle breakthrough is analyzed when the filter (optionally incorporated into a smoking article) is operably coupled to a smoking machine equipped with a particle counter configured to detect particles in the size range from about 0.3 micrometers to about 10 micrometers. Preferably the particle counter is a laser light scattering particle counter, such as AEROTRAK® particle counter. The smoking machine is preferably configured to take 12 puffs of 55 mL during 2 seconds every 13 seconds per filter (optionally incorporated into a smoking article). Preferably, particle breakthrough results are averaged from tests of a number of filters or smoking articles, such as five or ten or more filters or smoking articles.

The amorphous magnesium carbonate material may be utilized as a pure material or may be combined with or include other material such as crystalline magnesium carbonate to form a mixture of amorphous and crystalline magnesium carbonate material. The amorphous and crystalline magnesium carbonate material may have at least about 10% wt, or at least 25% wt, or at least 50% wt, or at least 75% wt, or at least 90% wt, or at least 99% wt amorphous magnesium carbonate material. The amorphous and crystalline magnesium carbonate material may have at least about 10% wt, or at least 25% wt, or at least 50% wt, or at least 75% wt, or at least 90% wt, or at least 99% wt crystalline magnesium carbonate material. The mixture of amorphous and crystalline magnesium carbonate material may include from about 25% to about 75% wt amorphous magnesium carbonate material, and from about 25% to about 75% wt crystalline magnesium carbonate material.

The amorphous magnesium carbonate material may be utilized as a pure material or may include magnesium oxide to form a mixture of amorphous magnesium carbonate and magnesium oxide material. The amorphous and crystalline magnesium carbonate material may have at least about 10% wt, or at least about 25% wt, or at least about 50% wt, or at least about 75% wt, or at least about 90% wt, or at least about 99% wt amorphous magnesium carbonate material. The amorphous and crystalline magnesium carbonate material may have at least about 10% wt, or at least about 25% wt, or at least about 50% wt, or at least about 75% wt, or at least about 90% wt, or at least about 99% wt crystalline magnesium carbonate material. The mixture of amorphous and crystalline magnesium carbonate material may include from about 75% to about 99% wt amorphous magnesium carbonate material, and from about 25% to about 1% wt crystalline magnesium carbonate material. The mixture of amorphous and crystalline magnesium carbonate material may include from about 90% to about 99% wt amorphous magnesium carbonate material, and from about 10% to about 1% wt crystalline magnesium carbonate material.

The amorphous magnesium carbonate material may be a homogenous amorphous material. The amorphous magnesium carbonate material may include regions or portions that are crystalline. The amorphous magnesium carbonate material may be at least about 50% by weight amorphous and less than about 50% by weight crystalline, or less than about 25% by weight crystalline, or less than about 10% by weight crystalline. The amorphous magnesium carbonate material may be at least about 75% by weight amorphous, or at least about 90% by weight amorphous.

The amorphous magnesium carbonate material is a sorbent material that may be utilized alone or with other sorbent materials. The sorbent material may be 100% wt amorphous magnesium carbonate material. The sorbent material may be less than 100% wt amorphous magnesium carbonate material.

The amorphous magnesium carbonate material may be mixed with activated carbon within the filter. The amorphous magnesium carbonate material and activated carbon may be mixed to form a sorbent mixture within the filter.

The amorphous magnesium carbonate material may be segregated from activated carbon within the filter. The amorphous magnesium carbonate material and activated carbon may be segmented from each other. The amorphous magnesium carbonate material may be separated from the activated carbon and may be downstream from the activated carbon. The amorphous magnesium carbonate material may be separated from the activated carbon and may be upstream from the activated carbon. The amorphous magnesium carbonate material may be separated from the activated carbon and may be both downstream and upstream from the activated carbon. The amorphous magnesium carbonate material may be separated from the activated carbon and may define a parallel arrangement where mainstream smoke or aerosol flows through the segmented sorbents in a parallel flow configuration.

The mixture or segregated total amount of amorphous magnesium carbonate material and other sorbent material, such as activated carbon, may include from about 25% to about 75% wt amorphous magnesium carbonate material, and from about 25% to about 75% wt other sorbent material, such as activated carbon. The mixture or segregated total amount of amorphous magnesium carbonate material and other sorbent material, such as activated carbon, includes from about 50% to about 95% wt amorphous magnesium carbonate material, and from about 50% to about 5% wt other sorbent material, such as activated carbon.

The amorphous magnesium carbonate material may exhibit a light color or a white color. The light or white color may provide or assist with maintaining visual aesthetics of the filter and filtration material. The amorphous magnesium carbonate material may have a color that is similar to the color of the filtration material. The amorphous and magnesium carbonate material may be difficult to see and may blend in with the filter and filtration material.

The amorphous magnesium carbonate material may be colored with a dye or pigment. The dye or pigment preferably is a food grade dye or pigment. The amorphous magnesium carbonate material may be colored green, yellow, red, blue, orange or purple, or any shade thereof.

The amorphous magnesium carbonate material may be contained within a plug-space-plug filter configuration where the amorphous magnesium carbonate material may be contained within the space or void in axial alignment with and separating the upstream and downstream plugs of filtration material defining the filter. The amorphous magnesium carbonate material may be unbound in the space or void. The amorphous magnesium carbonate material may not be contained within the space or void separating the upstream and downstream plugs of filtration material and instead be contained within the upstream or downstream plugs of filtration material defining the filter. This filter configuration may be free of activated carbon. This filter configuration may include a sorbent mixture comprising amorphous magnesium carbonate material and activated carbon, as described above. This filter configuration may include segregated sorbents comprising amorphous magnesium carbonate material and separate activated carbon.

The amorphous magnesium carbonate material may be contained within a multi-segment filter configuration where the amorphous magnesium carbonate material may be dispersed and contained within a single segment of filtration material and the remaining segment or segments (in axial abutting alignment) are free of the amorphous magnesium carbonate material. The amorphous magnesium carbonate material may be dispersed and contained within a single upstream segment of filtration material and the remaining downstream segment or segments are free of the amorphous magnesium carbonate material. This filter configuration may be free of activated carbon. This filter configuration may include a sorbent mixture comprising amorphous magnesium carbonate material and activated carbon, as described above. This filter configuration may include segregated sorbents comprising amorphous magnesium carbonate material and separate activated carbon.

The amorphous magnesium carbonate material may be contained within a single segment filter configuration where the amorphous magnesium carbonate material is dispersed and contained within a single segment of filtration material. This filter configuration may be free of activated carbon. This filter configuration may include a sorbent mixture comprising amorphous magnesium carbonate material and activated carbon, as described above. This filter configuration may include segregated sorbents comprising amorphous magnesium carbonate material and separate activated carbon.

The amorphous magnesium carbonate material may be contained within a concentric filter configuration where the amorphous magnesium carbonate material is dispersed and contained within an inner or outer concentric segment of filtration material. This filter configuration may be free of activated carbon. This filter configuration may include a sorbent mixture comprising amorphous magnesium carbonate material and activated carbon, as described above. This filter configuration may include segregated sorbents comprising amorphous magnesium carbonate material and separate activated carbon.

The amorphous magnesium carbonate material may be uniformly distributed within or throughout the filtration material or filtration segment. The amorphous magnesium carbonate material may be non-uniformly distributed within or throughout the filtration material or filtration segment. The amorphous magnesium carbonate material may be physically bound within the filtration material or filtration segment.

The filtration material described for the above configurations may be formed from cellulose esters such as cellulose acetate, polylactic acid (PLA), cellulosic material, polypropylene, cotton, flax, hemp, or any degradable filtration media, or a combination or blend of any two or more of filter materials. Cellulose esters include cellulose acetates, cellulose propionates and cellulose butyrates with varying degrees of substitution, as well as mixed esters thereof. Fibre tow filtration plugs may have from about 1.5 to about 8.0 denier per filament. Fibre tow filtration plugs may have a “Y”-cross section and from about 15,000 to about 50,000 total denier. The filtration material may be a crimped strip of nonwoven cellulose material (such as paper) that may be gathered together to form a plug.

The filter may contain any useful amount of amorphous magnesium carbonate material. The filter may contain from about 10 mg to about 200 mg, or from about 50 mg to about 150 mg, or from about 75 mg to about 125 mg of amorphous and magnesium carbonate material. The filter may contain from about 10 mg to about 200 mg, or from about 50 mg to about 150 mg, or from about 75 mg to about 125 mg of amorphous and magnesium carbonate material and sorbent mixture, such as activated carbon.

A smoking article filter may include amorphous magnesium carbonate material and activated carbon where the activated carbon forms less than about 50% wt of the sorbent present in the smoking article filter. A smoking article filter may include amorphous magnesium carbonate material and activated carbon where the activated carbon forms less than about 25% wt, or less than about 10% wt of the sorbent present in the smoking article filter. A smoking article filter may include from about 20 mg to about 150 mg of amorphous magnesium carbonate material and from about 10 mg to about 100 mg of activated carbon.

A smoking article filter may include amorphous magnesium carbonate material and activated carbon where the activated carbon may be upstream of the amorphous magnesium carbonate material.

Activated carbon is a generic term used to describe a family of carbonaceous adsorbents with an extensively developed internal pore structure. Activated carbon may be produced from a carbonaceous source material such as wood, lignite, coal, nuts, nut shells, coconut husk or shells, peat, pitch, polymers such as phenolic resins, cellulose fibers, polymer fibers, or the like. Activated carbon may be produced by any suitable process such as physical activation or chemical activation. In physical activation, the source material is developed into activated carbon by carbonization and activation with hot gases. The process of carbonization includes pyrolyzing source material at high temperatures, typically in the range of about 600° C. to about 900° C., in the absence of oxygen. Activation includes exposing carbonized material to oxidizing atmospheres, such as steam, carbon dioxide or oxygen, at temperatures above 250° C., such as about 800° C. Temperatures for activation/oxidization typically range from about 600° C. to about 1200° C., such as about 850° C. Chemical activation includes impregnating raw source material with certain chemicals, such as an acid, base or salt, such as phosphoric acid, potassium hydroxide, sodium hydroxide, calcium chloride, or zinc chloride. The raw materials are then carbonized at temperatures that are typically lower than physical activation carbonization. For example, temperatures for chemical activation carbonization may be in the range of from about 450° C. to about 900° C. Carbonization and activation may occur simultaneously.

Amorphous magnesium carbonate material may be placed in a smoking article downstream of a smokable material in any suitable manner. The term “downstream” refers to relative positions of elements of the smoking article described in relation to the direction of mainstream smoke as it is drawn from a smokable material and into a user's mouth. Preferably, the amorphous magnesium carbonate material is placed in a filter element.

A filter may have a diameter from about 5 mm and about 9 mm. A filter having a diameter of about 7.8 mm may be used in a “regular size cigarette” having an overall diameter of about 8.0 mm. The filter may have a length in a range from about 10 mm to about 30 mm, or from about 15 mm to about 25 mm.

A filter may have a diameter from about 3.6 mm and about 6.5 mm. A filter having a diameter of about 6.1 mm may be used in a “slim cigarette” having an overall diameter of about 7.0 mm. The filter may have a length in a range from about 10 mm to about 30 mm, or from about 15 mm to about 25 mm.

A filter may have a diameter from about 3.6 mm and about 5.5 mm. A filter having a diameter of less than about 4.5 mm may be used in a “super slim cigarette” having an overall diameter of less than about 5.4 mm. The filter may have a length in a range from about 10 mm to about 30 mm, or from about 15 mm to about 25 mm.

A filter may have a diameter from about 3.6 mm and about 4.5 mm. A filter having a diameter of about 3.8 mm may be used in a “micro slim cigarette” having an overall diameter of about 4.7 mm. The filter may have a length in a range from about 10 mm to about 30 mm, or from about 15 mm to about 25 mm.

The term “smoking article” includes cigarettes, cigars, cigarillos and other articles in which a smokable material, such as a tobacco, is lit and combusted to produce smoke. The term “smoking article” also includes articles in which smokable material is not combusted, such as smoking articles that heat a smoking composition directly or indirectly, or smoking articles that use air flow or a chemical reaction, with or without a heat source, to deliver nicotine or other materials from the smokable material.

As used herein, the term “smoke” is used to describe an aerosol produced by a smoking article. An aerosol produced by a smoking article may be, for example, smoke produced by combustible smoking articles, such as cigarettes, or aerosols produced by non-combustible smoking articles, such as heated smoking articles or non-heated smoking articles.

All scientific and technical terms used herein have meanings commonly used in the art unless otherwise specified. The definitions provided herein are to facilitate understanding of certain terms used frequently herein.

The terms “upstream” and “downstream” refer to relative positions of elements of the smoking article described in relation to the direction of inhalation air flow as it is drawn through the body of the smoking article from a distal end portion to the mouthpiece portion.

All scientific and technical terms used herein have meanings commonly used in the art unless otherwise specified. The definitions provided herein are to facilitate understanding of certain terms used frequently herein.

As used herein, the singular forms “a”, “an”, and “the” encompass embodiments having plural referents, unless the content clearly dictates otherwise.

As used herein, “or” is generally employed in its sense including “and/or” unless the content clearly dictates otherwise. The term “and/or” means one or all of the listed elements or a combination of any two or more of the listed elements.

As used herein, “have”, “having”, “include”, “including”, “comprise”, “comprising” or the like are used in their open-ended sense, and generally mean “including, but not limited to”. It will be understood that “consisting essentially of”, “consisting of”, and the like are subsumed in “comprising,” and the like.

The words “preferred” and “preferably” refer to embodiments of the invention that may afford certain benefits, under certain circumstances. However, other embodiments may also be preferred, under the same or other circumstances. Furthermore, the recitation of one or more preferred embodiments does not imply that other embodiments are not useful, and is not intended to exclude other embodiments from the scope of the disclosure, including the claims.

FIG. 1 is a schematic perspective view of an embodiment of a partially unrolled smoking article.

FIG. 2 is a schematic diagram cross-section view of an illustrative plug-space-plug filter for a smoking article.

FIG. 3 is a schematic diagram cross-section view of an illustrative single segment filter for a smoking article

FIG. 4 is a schematic diagram cross-section view of an illustrative concentric filter for a smoking article

FIG. 5 is a schematic diagram mouth end view of an illustrative crimped paper filter for a smoking article.

The schematic drawings are not necessarily to scale and are presented for purposes of illustration and not limitation. The drawings depict one or more aspects described in this disclosure. However, it will be understood that other aspects not depicted in the drawings fall within the scope and spirit of this disclosure.

Referring now to FIG. 1, a smoking article 10, in this case a cigarette, is depicted. The smoking article 10 includes a rod 20, such as a tobacco rod containing cut or loose tobacco material, and a mouth end filter 30 that includes filtration material 32, such as cellulose acetate fibre tow or polylactic acid filter material. The depicted smoking article 10 includes plug wrap 60, cigarette paper 40, and tipping paper 50. In the depicted embodiment, the plug wrap 60 circumscribes at least a portion of the filter 30. The cigarette paper 40 circumscribes at least a portion of the rod 20. Tipping paper 50 or other suitable wrapper circumscribes the plug wrap 60 and a portion of the cigarette paper 40 as is generally known in the art. The filter 30 includes amorphous magnesium carbonate, as described above, which may be placed as depicted in, for example, FIG. 2, FIG. 3, FIG. 4 or FIG. 5.

FIG. 2 illustrates a plug-space-plug filter embodiment where filter 30 is in a plug 32-space 33-plug 34 configuration. Plug 32 is the mouth end plug and is preferably white cellulose acetate tow. Amorphous magnesium carbonate material or particles 80 are disposed in void space 33 between plugs 32 and 34. The particles 80 are illustrated as floating in free space for ease of illustration. The particles 80 may fill the void or space 33 segment or fill a portion of the void or space 33 segment. Plug wrap 60 circumscribes at least a portion of the filter 30.

FIG. 3 illustrates a single segment embodiment filter 30 where the filter 30 contains amorphous magnesium carbonate material or particles 80 is dispersed within and embedded in filter material 32. Plug wrap 60 circumscribes at least a portion of the filter 30.

FIG. 4 is a schematic diagram cross-section view of an illustrative concentric filter 30 where the amorphous magnesium carbonate material or particles 80 is dispersed within and embedded in an inner filter material 32 and circumscribed with an outer filter material 31. The inner filter material 32 may have a lower resistance to draw (RTD) than the outer filter material 31. Plug wrap 60 circumscribes at least a portion of the filter 30.

FIG. 5 is a schematic diagram mouth end view of an illustrative crimped paper filter 30 where the amorphous magnesium carbonate material or particles 80 is dispersed within and embedded in a strip of crimped paper 40 that is gathered to form the filtration material. Plug wrap 60 circumscribes at least a portion of the filter 30. FIG. 5 illustrates amorphous magnesium carbonate material or particles 80 bound to a surface of the crimped paper filter 30, it is contemplated that the amorphous magnesium carbonate material or particles 80 may be embedded within the crimped paper filter 30, or extend through the thickness of the crimped paper filter 30. The amorphous magnesium carbonate material or particles 80 may extend through both opposing major surface of the crimped paper filter 30.

In the following, non-limiting examples provide illustrative embodiments of a smoking article filter containing amorphous and magnesium carbonate material or particles described above. These examples are not intended to provide any limitation on the scope of the disclosure presented herein.

EXAMPLES

A plug-space-plug filter having a 5 mm space was utilized to compare a charge of porous cellulose beads (commercially available under the trade designation VISCOPEARL) and a charge of amorphous magnesium carbonate material both exposed to tobacco smoke utilizing the Intense Smoking of Cigarettes test method. This smoking regime or protocol utilized was the World Health Organization Tobacco Laboratory Network Standard Operating Procedure for Intense Smoking of Cigarettes (SOP01, April 2012). This method utilizes ISO 3308 but is modified by blocking all ventilation holes present on the cigarette as described in SOP01 for intense regimen testing. Two cigarettes were smoked per pad of 92 mm in triplicate.

A first run utilized 100 mg of VISCOPEARL porous cellulose beads contained within a plug-space-plug filter and an amount of tobacco smoke was passed through the plug-space-plug filter in accordance with the test method described above.

A second run utilized 100 mg of amorphous and magnesium carbonate material (400 micrometer to 1000 micrometer size particles), as described above, contained within a plug-space-plug filter and an amount of tobacco smoke was passed through the plug-space-plug filter in accordance with the test method described above.

The plug-space-plug filter containing the amorphous and magnesium carbonate material reduced formaldehyde by about 23%, water by about 10%, and benzene by about 1% in the tobacco smoke as compared to the values determined for the plug-space-plug filter containing the VISCOPEARL porous cellulose beads. Nicotine levels remain substantially the same for the plug-space-plug filter containing the amorphous magnesium carbonate material and the plug-space-plug filter containing the VISCOPEARL porous cellulose beads.

Thus, methods, systems, devices, compounds and compositions for SMOKING ARTICLE FILTER WITH AMORPHOUS MAGNESIUM CARBONATE are described. Various modifications and variations of the invention will be apparent to those skilled in the art without departing from the scope and spirit of the invention. Although the invention has been described in connection with specific preferred embodiments, it should be understood that the invention as claimed should not be unduly limited to such specific embodiments. Indeed, various modifications of the described modes for carrying out the invention which are apparent to those skilled in chemistry; chemical engineering; filter manufacturing; cigarette manufacturing; or related fields are intended to be within the scope of the following claims. 

1. A filter for a smoking article comprising, filtration material and an amorphous magnesium carbonate material contained within the filtration material.
 2. The filter according to claim 1, wherein the amorphous magnesium carbonate material is hygroscopic, wherein the amorphous magnesium carbonate material physically adsorbs at least about 1.5 mmol water/g at a relative humidity of about 10% at about 27 degree Celsius and one Atm.
 3. The filter according to claim 1, wherein the amorphous magnesium carbonate material has a BET surface area of at least about 300 m2/g.
 4. The filter according to claim 1, wherein the amorphous magnesium carbonate material has an average particle size in a range from 100 micrometres (about 140 mesh) to about 2000 micrometres (about 10 mesh).
 5. The filter according to claim 1, wherein the filter comprises about 10 mg to about 200 mg of amorphous magnesium carbonate material.
 6. The filter according to claim 1, wherein the filter comprises a mixture of crystalline magnesium carbonate material and amorphous magnesium carbonate contained within the filtration material.
 7. The filter according to claim 1, wherein the filter comprises a mixture of magnesium oxide material and amorphous magnesium carbonate contained within the filtration material.
 8. The filter according to claim 1, wherein the filtration material comprises a plug of tow material and the amorphous magnesium carbonate material is dispersed within the plug of tow material, and the tow material preferably comprises cellulose acetate.
 9. The filter according to claim 1, wherein the filter is a segmented filter comprising two filtration elements in axial alignment and separated by a void space, the void space containing the amorphous magnesium carbonate material.
 10. The filter according to claim 1, wherein the filter is a segmented filter comprising an upstream filtration element in axial alignment with a downstream filtration element, the upstream filtration element containing the amorphous magnesium carbonate material, and the downstream filtration element is free of the x-ray amorphous magnesium carbonate material.
 11. The filter according to claim 1, wherein the amorphous magnesium carbonate material comprises bound water.
 12. The filter according to claim 1, wherein the filter is free of activated carbon.
 13. The filter according to claim 1, further comprising activated carbon contained within the filtration material.
 14. A smoking article comprising: smokable material; a filter, according to claim 1, downstream of the smokable material.
 15. The smoking article according to claim 14, wherein the smokable material comprises tobacco, or cut tobacco.
 16. The filter according to claim 1, wherein the amorphous magnesium carbonate material has a BET surface area within a range from about 300 m2/g to about 1200 m2/g.
 17. The filter according to claim 16, wherein the amorphous magnesium carbonate material has an average particle size in a range from about 200 micrometres (about 70 mesh) to about 1500 micrometres (about 14 mesh).
 18. The filter according to claim 17, wherein the amorphous magnesium carbonate material is hygroscopic, wherein the amorphous magnesium carbonate material physically adsorbs at least 2 mmol water/gram, at a relative humidity of about 10% at about 27 degree Celsius and one Atm.
 19. The filter according to claim 18, wherein the filter comprises a mixture of crystalline magnesium carbonate material and amorphous magnesium carbonate contained within the filtration material.
 20. A smoking article comprising: smokable material; a filter, according to claim 19, downstream of the smokable material. 